The United States is delivering an additional 1.5 million Covid-19 vaccine doses to Taiwan, a senior US administration official told Reuters, increasing to 4m the total number of shots donated by Washington to the self-ruled island, which is under increasing pressure from China.

“Our vaccines do not come with strings attached” and were not donated to “secure favours or extract concessions,” the Biden administration official said, in an apparent reference to criticism that Beijing is trying to strengthen its geopolitical clout through so-called vaccine diplomacy.

The US gave 2.5m doses to the island claimed by China in June, making it among the first international recipients of U.S. vaccines.